Speed change gear



Jan.9, 1945. w. LAUPER 2,366,912 4 SPEED CHANGE GEAR n .Filed sept. 24,1942 2 sheets-sheet 1 lw Ww 27g-.l l 496 im@ I4 f 44 pered towardsPatented Jan. `9, 1945 UNITED. STATES PATENT OFFICE" 2,366,912 SPEEDCHANGE `GEAR Werner Lauper, Bienne, Switzerland, `assigner to NouvellevZesar S. A., Nidau, f near Bienne,

Switzerland, a @land i joint-,stock company of Switzer- `Application.September 24, 1942, Serial No. 459,569

` In Switzerland April 23,1941 l, i i

relaas. (cmi-577) The objectof the present invention is a speed changegear specially but not exclusively for bicycles, in which the speedchange is obtained by rotating the driving shaft backwards and in whichthe transmission gear wheels connected with the `driven member on thedriven shaft are controlled by pairs of spring-controlled pawls n thedrivf` ing shaft.

This invention relates `to improvements of `this typeof speedchangegears. The springs operating the above-mentioned pawls hadhitherto the disadvantage that` they jammed in the recesses of thedriving shaft in whichthey were supported and that often a side bucklingof the Part lying outside theser'ecesses occurred.,` This `resulted inannoying disturbances.

After many tests aspring construction hasbeen found by which both theabove-mentioned side buckling and the jamming are avoided. Thisconstruction is characterised in thatthe springs acting upon the pawlsare supported on these latter by means of joints.`

` In a preferred embodiment the springs are ta- The accompanying`drawings illustrate, by wayv `of example, one embodiment of the objectof the inventionl l Fig. 1 is an axial section through the gear;

" Fig. 2 `is a section along the line II-II in Fig. l;

Fig. 3 is a section along the line III- III of Fig. 1;

Fig. 4 shows a pawl with a state; and

Fig. 5 the same but with released spring. U

The illustrated speed change gear has three speed stages and is such anembodiment of the gear type mentioned above, in which each pair of pawlsconsists `of twopawls adapted to be lowered into the driving shaft andmounted on a bolt arspring in compressed their supporting means on thehension` ofthe general arrangement` and of the invention. l l

` Thel tread cranks `I'are fixedto the tread crankshaft 2. Onjthelatterthe gearwheelsB, 4, 5 are loosely arranged and 'arein permanentengagement with the toothed` rims 6, 1, 8 of thewheel 9. The latter ismounted by means of the roller bearings l0 von the counteraxle Il which,onits part, is supported 'in bushings I2, I3 of the casing and is lockedagainst rotation by means of thepin I5. The hub `lli ofthe `gear wheel 5to which, besidesthe chain Wheel Ilof the bicycle `is fixed is pivotallymounted on the casing I4 by means ofthe roller bearing i8, The crank-`shaft 2 is likewise supportedY on roller'bearings `and that, at the oneend, on thehub I6 `by means "lof the iroller bearings 22 and, at theother end,

bya roller bearing 23"on the adjustingdish24. 3 inthe longitudinalgrooves ilZ` of the crankshaft.2lie the axles 34, 35, 36 which arefixed` a known manner to the shaft 2 or to parts fastenedto the saine.Each of these axles carries two pawn 31a anden, 38a, sab, senese. A11

ranged in a longitudinal groove of this shaft, one

of these pawls cooperating with a change speed wheel rotatably mountedon the driving shaft,

` while the other pawl is in `operating relation with a changing discwhich, on rotating the driving shaft backwards, brings the pawlscooperating with the change speed wheels one after the other in and outof engagement with these latter, the whole being such that the gear canbe changed from each speed stage to any other stage by a single backmovement and a subsequent forward movement of the driving shaft.

In the following statement the gearis only describedin'so far as isnecessary for the compre- `the b-pawls lie in aplane `perpendicular tothe crankshaft?, while theipawl`3la isfwithin reach of the wheel 3, thepawl 38a within reach of the wheel 4 and the pawl 39a Within reach ofthe `wheel 5` The crankshaft 2 has `recesses 40 into. "which the pawlscan enter. l `The a-pawls jcan be Aalternately brought in` and out of*engagement with the gear Wheels 3, 4 and 5 in order to render differentgear` ratios between the crank shaft 2` and the chain wheel. I1 possiblewith these wheels 3, 4, 5 and the toothed rims 6, 'l and 8. Therefore,the wheels 3 and4 and the sleeve 44 which,y takes the wheel 5 along,have cut-outs 4|, 42 and` 43 which can be engaged by the pawls 31a, 38a

and 39a to take the wheels 3, 4 and 5 along. Springs 45 act upon theb-pawls,.which tend to throw these b-pawls out of the recesses 40. Theyrest in cut-outs, e. g., bores 46 of the crankshaft 2 and are tapered,e. g., conically tapered towards the pawls. At the tapered end of eachspring 45 a joint head 41 rests, e. g., of spherical form which isplaced upon the spring 45 by means l of the pin 63 andcooperates with acorresponding joint cup 48 of the b-pawls. The tapering of the springs45 and their pivotal support by means of the head 41 and cup 48 preventsa side buckling of the spring and a jamming of the same in the bores 46;both in the released state (Fig. 5),.and in the compressed state (Fig.4),

the spring axis remains at least approximately in the line A--B. l

A change disc 49 is arranged on the crankshaft 2 within reach of theb-pawls, this change disc having a curved cut-out 50. The latter, at one'end, runs gradually into the bore of the disc 49 and, at the other end,forms a supporting surface 5I. The cut-out 50, when lying opposite of ab-pawLalloWs ,the latter to be thrown out. The change disc 49 has twotoothed rims 49a andr49b lying in two diierent planes and havingcounterpointed teeth.

On the axle I I a back disc 52 is provided which carries a spring-loadedpawl 53 and which can be turned until it strikes against the stops 54.The back disc has a tooth 55 intended to cooperate with the teeth 49hofthe change disc 49. Besides this, the back disc 52'has a curvedprofile 58 cooperating with a spring-loaded lever 51. The back disc 52,together with the lchange disc 4.9;

serves the purpose of controlling thelchanging yof the speed changegear.

The. change speed gear isvoperated as follows: -'fNile-vvil1`supposethat the carrier pawl corresponding to gear Wheel 4 be effective,thatis that 'dog/Stbe engagednwith ,one ,of/the notches 42 -paw1l53landturn thestop plate A52 vinto thefposivtion of Fig.' 2;. `The .controldisk .is `thereby stopped,f but "the .shaft'i f2 continues turning.

Therefore; At'h`ez"-do 38h projecting into the-*out out'501wil1`leave hiecess and be pressed back `into its recess'4i0together withgthecorresponding dog 38a Which lis also `sunk intozits recess 40 of thecrankshaft a'ndfis` disengaged therefore from the gearfwheel 4".A ANovvbythe continued back- Dedaliiigl dog l-3917- willtaketheplace of-.dQg-Sb fandicqme itoface therecess 50 'and will be ex- Y pelled by itsspring 45 from .its recess 40 in the crankshaft` whenv the cooperatingdogf 39a can -drop intoarecess -4'3`1ofxthezgear wheel 5. I'f this dogdoes noti face said recess, dog 3'9b'remains within its recess 4U.

The crankshaft is nowturnedagain in a clockwise v-direction,(liigz 2)'and `then'the ycontrol `disk `in the gear. .Wheel 4'. .Then dog 38h-anddisk 4,9 l

tooth 55, because arm 51 has been engaged by the notch 56 of stop plate52. As soon as dog 39h bears against the shoulder 5|, the stop plate 52is brought back against the effect of arm 5'! into its rst position. Thespacing of the notches 4I, 42, and 43 of the gear wheels carried by thecrankshaft amounts to about one-half the length of the arc of recess sothat in the-above mentioned case, where after the change the succeedingdog a could not engage one of the recesses 4i, 42L 43, such engagingbecomes impossible during the clockwise rotation of the crankshaft.

If at the end ofthe back-pedaling, the control disk 49 advances in sucha position with respect to dogs b, in which the dog facing the recess 50is kept Within its recess by the portion of the cut out recedinginto'the bore, this dog will be brought into engagement with theshoulder 5|, owing to thestopping of the control disk by the stop platewhen the shaft is again pedaled in a clockwise direction. Inthispositiona complete engagement of said dog va is lalways possible. Thus-care has.been taken thatinno case a dog be engagedonly `partially'or notat all.-

If it is desiredv to `jump one step, it suflices,

Ias may be vseen fromthedrawings, to back pedal theshaft for.two-thirdsrevolution instead-of only one-third revolution. Then theoperations `as .described will take .place with the difference thatthedogb,.which corresponds to the jumpedstep will pass the recess 50 sothat it projects into said depression for only a short time and will beimmediately afterwards` disengagedagain and depressedinto the recess ofthe crankshaft. Only .the following dog b will be engaged with theshoulder 5I by a stopping of What IV claim is: Y In astructure of thecharacter described, a rotatable shaft `having a peripheral .recess,`apawl pivotally connectedto the shaft and movable into the shaft.

`.said recess, said pawl having a substantially semispherical cavity, VaIsubstantially conical coil spring having its largest end seated .in therecess .the vspring being unsupported throughout its length, asubstantially semi-spherical head secured to the outer end of .thespring and slidably engaging thesurface vof the cavity,.and ya ypin Xedto the head and extending into the smaller .end portionpf4 the spring.

A WERNER. LAUREE.

